Treatment of fourdrinier wire



y 7, 1964 R. LJpMlCHALSKl ETAL 3,140,222

TREATMENT OF FOURDRINIER WIRE Filed Dec. 22. 1961 Inventor's Ragmond J. Michalski Theodore R. N w 3 Marga/l, Johnsion COOkAzRooi' ATHZO r'rz eks V United States Patent O This invention relates to a method for improving by chemical means the operational efliciency of a Fourdrinier paper making machine. More specifically, the invention is concerned with extending the life of Fourdrinier wires commonly employed in Fourdrinier paper making machines.

One of the most versatile machines used in the manufacture of paper is the well-known Fourdrinier paper making machine. Utilizing machines of this type, a Wide variety of paper products are produced in mills located throughout the entire United States. Such conventional paper and paper products as bags, building boards, paper boards, various book stocks, and such specialized paper products as carbon paper stocks, cigarette papers, glassine and greaseproof papers, napkins, newsprint, pulp tissue, wrapping, and Writing stocks may be produced on Fourdrinier machines.

As Fourdrinier machine technology has been improved over the years, there has been an increased tendency to use Fourdrinier machines which operate at extremely high speeds. While high speed Fourdrinier paper making machinery enables the mills using such machines to produce large tonnages of various types of paper and paper products, there is a disadvantage encountered in that the abrasive wear of the Fourdrinier wire used in the machine is excessive. The life of a typical Fourdrinier wire, particularly in a high speed machine, is short. In some instances, Fourdrinier wires only last several days whereas in other cases, particularly on slower speed machines, it is possible for a Fourdrinier wire to last for as long as several weeks to a month or more. In complex Fourdrinier machines, Fourdrinier wire replacement becomes an expensive and time consuming operation when it is considered that production must stop and elaborate procedure must be followed in order to replace the Fourdrinier wire. Depending upon the particular type of paper being produced on the machine, the cost of a new Fourdrinier wire can range from as little as $3500 to as much as $5000, or more. When the wire costs are considered in conjunction with labor costs required to install Fourdrinier wires, it is readily apparent that any method, either chemical or physical, for reducing wire loss by extending the life of a Fourdrinier wire without sacrificing speed or production would be a valuable benefit to the paper making industry.

Numerous mechanical solutions to Fourdrinier wire wear have been proposed. They have met with only limited success. Most mechanical systems for improving Fourdrinier Wire life involvesthe installation of expensive rolls and tension regulating devices, and to this end their installation is only practical in the design of new machinery and is not particularly adaptable to be installed in existing Fourdrinier machines. A practical approach to the problem of reducing the wear and extending the life of Fourdrinier wire resides in the use of chemicals whereby the wire may be treated at low economical dosages, either intermittently or on a continuous basis, to substantially increase the operating life of a Fourdrinier wire.

For a chemical treatment to effectively improve the life of Fourdrinier wires, it is necessary that it perform several vital functions which will tend to alleviate the basic problems which cause Fourdrinier wire wear.

Microscopic examination of worn Fourdrinier Wires has made it evident that there are numerous factors which effect wire life. One of the most common factors caus-. ing Fourdrinier wire failure is the abrasive wear caused by a friction between the bottom of the wire and the suction boxes, forming boards, and deflectors. Most of this wear occurs at the suction boxes. A serious form of abrasive wear comprises the burring of the bottom of the wires, particularly the warp knuckles. In some cases, bare spots develop in wires. This is most com-. monly attributed to the forming of foreign substances which are entrapped in the wire.

Other types of Wear in Fourdrinier wire may be ascribed to frictional effects and present themselves as worn wire in the forms of scores and distortions. Fre-. quently excessive wire wear may be attributed to poor drainage characteristics, either because of improper vacuum on the suction boxes or other similar reasons. Also, a poor quality Water will cause scaling and edge filling. Similarly, due to mechanical characteristics of the Wire, edge cracks, edge splits, and edge distortion frequently occur in Fourdrinier wires operating on various types of Fourdrinier machines.

A factor which sometimes tends to accelerate abrasive Wear of Fourdrinier wires is corrosion. In and of itself, corrosion is not particularly damaging to Fourdrinier wire, but it tends to substantially reduce abrasion resistance and draining characteristics of the wire so that frictional effects imposed on the wire are increased.

A careful study of the above types of wear of a Fourdrinier wire leads one skilled in the art to the obvious conclusion that if abrasive wear or frictional properties of Fourdrinier wire, caused by its contacting the various parts and sections used in a Fourdrinier machine, could be reduced and if the drainage characteristics of the wire could be improved, thereby preventing blockage by either fiber or foreign substances, then a practical solution to the extension of Fourdrinier wire life could be achieved.

Therefore, if a chemical treatment is to succeed in improving the operation characteristics of a Fourdrinier paper making machine by the extension of the useful life of the Fourdrinier wire used in such machines, such a treatment must function in a two fold manner, e.g., it must be capable of both preventing abrasive wear by providing a lubricating action on the wire, and secondly, it mustact as a dispersant or cleansing agent to prevent orto remove deposits between the open areas defined by the mesh of the particular wire used. It therefore becomes an object of the invention to provide a chemical treament, which when applied in low, economical dosages, will improve the operational efficiency of a Fourdrinier paper making machine.

I Another object of: the invention is to provide a chemical which will substantially reduce the abrasive wear of Foudrinier wires.

A further object is to provide a chemical which will machine may be greatly improved by treating the bottom of the wire with a water soluble, extreme pressure lu bricant and either a nonionic or anionic, Water dispersible wetting agent. By using this combination of ingredients is is possible to treat Fourdrinier wire with as little as .005 pound of treating agent per ton, based on the weight of the paper formed on the wire with the above combination of chemicals, to substantially increase wire life. The chemicals have a twofold effect in that they afford lubricity and improve the drainage of the stock formed, thereby providing a surface which has less tendency to abrade than an untreated wire, when passing over the various sections of a typical Fourdrinier machine. Our investigations have led us to believe that localized areas of stress are excessive to the point that high pressures are involved. This means thatconventional lubricants are of little value in the solution of the problems enumerated above.

For a more comprehensive understanding of how the compositions of the invention are applied to improve the operational characteristics of a Fourdrinier machine, reference may be had to the drawing.

The drawing is a simple schematic diagram of a typical Fourdrinier end of a paper making machine. The numerals used in the drawing represent the various com ponents of the Fourdrinier system. It is to be understood that the drawing is simplified, but serves to illustrate generally a typical Fourdrinier system. The headbox and slice area are generally represented by the numerals 1 and 2 respectively. The breast roll is illustrated by the numeral 3 whereas the deckle rolls and forming board are shown by the numerals 4 and 5. The table roll 6, tray 7, and suction flat boxes 8 are another common group of components found in Fourdrinier machines.

The couch roll 9, dandy roll 10, and lump breaker roll 11, might be considered as ending the top section of a typical Fourdrinier assemblage. Wire showers 12, wash rolls 13, automatic guide rolls 14, stretch rolls 15, and wire return rolls 16 and 16A all compose what is generically referred to herein as the return section of the Fourdrinier wire, and operate to control the bottom movement of the wire. The wire itself is indicated by the numeral 18. An important concept of the invention resides in the use of a shower applicator 17 which is located between a wire return roll 16A and the breast roll 3. This shower spray is a preferred application point for applying the wire life extending chemicals of the invention. It is obvious that the spray 17 should be positioned so that it uniformly sprays the chemicals onto the entire width of the wire 18.

To be effective, it is desirable that the chemical be applied to the bottom of the wire. The word bottom is used to refere to any point in the return section of the Fourdrinier wire between the couch roll 9 and its point of subsequent contact with the breast roll 3. This wire bottom section is admirably suited for application of the treating agent. It is preferable that the application point he as near the breast roll as possible.

An alternative method of applying the chemicals of the invention would be to coat the chemicals by suitable means (not shown) on the wire return roll 16, whereby the bottom of the wire would be coated uniformly. Regardless of the mode of application, it is important that the entire wire 18 be covered with the chemical and that the chemical be applied in the form of a dilute aqueous solution.

From the above description it is apparent that the chemicals in the invention are most preferably applied as a dilute aqueous solution to the bottom of the wire just prior to its engagement with the stock entering from the headbox 1 through the slice 2. The application of a dilute aqueous solution may be achieved by dissolving the chemicals into a suitable water source (not shown) and thereby applying them through the header or spray 17. The chemicals may be prepared initially either as dry chemicals to be subsequently diluted at the mill site or point of use, or they may be made up into an aqueous concentrate for efiiciency in shipment to the mill site where it may be diluted by the machine operators.

The water soluble, extreme pressure lubricants are sulfhydryl-containing compounds. They may be classified broadly as nitrogen-containing heterocyclic compounds characterized by a ring nitrogen bonded to a ring carbon. To the ring carbon is attached a non-ring sulfhydryl group. The characteristic structural formula covering this sulfhydryl heterocyclic combination of elements may be illustrated by the Formula I below:

FORMULA I ll ("-sn Compounds having this illustrative molecular configuration and which are valuable in the practice of the invention are such well-known compounds as Z-mercaptothiazole, 2 mercaptobenzimidazole, Z-mercaptobenzoxazole, and Z-mercaptobenzothiazole. Of these compounds, Z-mercaptobenzothiazole is preferred since it is relatively inexpensive and is commercially available.

The above compounds are, for practical purposes, relatively water insoluble, but they are rendered readily soluble by converting them to their alkali metal salts. Any of the well-known alkali metal salts of these compounds, e.g., sodium, potassium, cesium, and rubidium may be used, although due to availability and economics, the sodium salts are preferred. Equivalent to the sodium salts of these compounds are the ammonium salts, but they are not particularly preferred due to volatility problems encountered when the machines are operated at elevated temperatures.

The water miscible anionic and nonionic dispersing agents which may be used to improve the drainage characteristics and thereby decrease the abrasiveness of the wire may be selected from a large number of well-known chemicals. In the case of the anionic detergents, the well-known alkaryl sulfonic acids and their alkali metal salts, such as sodium dodecylbenzene sulfonate may be used as well as the alkali metal salts of sulfonated alcohols and the sulfonated lignins.

Although anionics may be used in the practice of the invention, it is preferred that a nonionic wetting agent be combined with the water soluble, extreme pressure lubricant. A preferred class of nonionic materials are the alkyl substituted ethoxylated phenols which are generically illustrated by structural Formula II.

FORMULA II In the above formula, R is an alkyl group of from 8 to 20 carbon atoms and n a positive integer having a value of not more than 20. A product falling in this group is dodecyl phenol which had been reacted with 9 moles of ethylene oxide.

Other suitable nonionic wetting agents are the wellknown Pluronic materials which are block copolymers of propylene and ethylene oxide and are described in US. Patent 2,674,619.

For a more comprehensive and detailed list of various nonionic and anionic wetting agents that may be used, reference may be made to the publication, Detergents and Emulsifiers to Date, by John W. McCutcheon, John W. McCutcheon, Inc., 1960.

In treating the Fourdrinier wire to provide increased life during its normal operation, the chemicals are fed at a relatively low dosage, e.g., .005 pound per ton based on the dry weight of the paper formed on the Fourdrinier wire, with the preferred dosage being from 0.025 to 0.1 pound per ton.

The wetting agents and the water dispersible, water soluble, extreme pressure lubricants are combined so as to provide a composition containing from 5 to 98% by weight of the water soluble, extreme pressure lubricant and from 2 to 95% by weight of the water miscible nonionic and anionic dispersing agent. The proportions of the two ingredients, of course, may be varied, depending upon the particular condition of the Fourdrinier machine and wire to be treated. For example, if it is determined that abrasive wear is due ex tensively to plugging of the mesh openings of the wire, then it would be desirable that a larger quantity of surface active agent be employed, whereas if abrasive wear is the predominant problem, then the amount of water soluble extreme pressure lubricant should be increased.

The compositions of the invention may be either formulatecl as a dry mix and then diluted at the point of use, or preferably, they are prepared as an aqueous concentrate which is then diluted to use concentration.

A typical composition useful in the practices of the invention is the aqueous concentrate illustrated by Formula III below:

FORMULA III Ingredients: Percent by weight Sodium Z-mercaptobenzothiazole 40 Isopropanol 7.5 Dodecyl phenol reacted with 9 moles of ethylene oxide 2.5 Soft water 50 1 Freezing point depressant.

While products of the type illustrated above in Formula III have been eminently successful in improving the operational characteristics of Fourdrinier paper making machines, it has been discovered further that the formulas may be improved in their efiicacy, particularly in cases where suction box friction is extremely great, by incorporating with such formulas, from 0.001 to .5 by Weight of a water dispersible, organic silicon containing compound.

The silicon containing compounds may be of two general types, the first being an organo silicon oxide condensation product which encompasses such well-known products as the condensed esters or" ortho and metasilicic acid and the well-known silicon polymers such as the poly dirnethyl siloxanes. Products of this general type are described in detail in Trautman et al., US. 2,416,- 503-4. When silicon containing compounds of this type are used, it is important that they be at least colloidally dispersible in water. When the compounds are not dispersible per se it is possible to form them into a sufficient state of subdivision, e.g., 1 micron or less, thereby making it possible to colloidally disperse such silicon containing compounds into the water and to this extent they are usable. A preferred group of silicon containing compounds are the organo functional silanes generically represented by Formula IV:

FORMULA IV R(o),.siY

(?)D R In the above formula, R is a lower aliphatic hydrocarbon group of not more than 4 carbon atoms in chain length. Y is an aliphatic amine-containing group and n=0 or 1. Typical examples of compounds coming within the above structural formula are gamma-aminopropyl triethoxy silane, delta-amino butyl methyl-diethoxy silane and 2-(3-trimethoxy silyl propylamino) ethyl amine. The above described water dispersible, organic silicon-containing compounds not only tend to improve the lubricating characteristics of the formula, but they also in some instances act as a defoaming agent to prevent excessive foam formation at the point of formula application.

To illustrate the invention the following are presented by way of example.

Example I This test was conducted in a paper mill producing unbleached kraft liner board on a Fourdrinier machine wire at operating speeds between 500 and 1350 linear feet per minute. Fourdrinier wire life experience was such that a typical wire lasted between 8 and 10 days. Inspection of the wire indicated that abrasive degradation was occuring due to the passing of the wire over the suction boxes. Formula III was injected onto the wire via a spray header located between the breast roll and the table roll with the dosage being started initially at .15 pound per ton for several hours and then being reduced to 0.1 pound per ton. At the end of several months testing it was obvious that the wire life dramatically increased. Some runs allowed a machine to operate for 20 days, with the shortest wire life being 12 days. Inspection of the wire always showed that it was clean with little or no plugging with either cellulosic material or foreign matter of any kind.

Example II In an unbleached kraft mill, one machine produced kraft board and paper at a rate of 1200 to 2100 linear feet a minute. Normal wire life at this mill average 7% days. Formula III was applied to the bottom of the wire by means of a spray located near the breast roll at a dosage ranging between 0.08 to 0.25 pound per ton. The test extended for several months and at the end of this time it was calculated that wire life was extended to an average of 10 /3 days. This is, of course, a substantial increase over the original wire life average experienced before the treatment. The treatment improved and maintained the drainage characteristics over the drainage achieved on a new wire at the start of the test.

The above examples illustrate that the dosage rates may be varied. Experience under actual mill conditions have shown it to be desirable to intially pretreat the wire by applying for a short period of time, e.g., several hours to several days, a rather large dosage which is then reduced to a minimal amount. Thus, a typical mill system, it would be desirable to treat at 0.25 pound per ton With a composition such as Formula III for several hours and then maintain a dosage of 0.1 pound per ton. This allows a protective coating of the wetting agent and a water soluble extreme pressure lubricant to sufficiently coat itself on the wire and to provide a lubricant type base on the wire which is then maintained by the subsequent continual dosage. It is possible to slug feed the treatments intermittantly to the bottom of the wire, but is a preferred practice that the chemical treatment be maintained continually through the entire life of the particular wire to achieve maximum wire life extension.

An important result as shown above, achieved by practicing the invention is the great improvement noticed in the drainage of the stocks formed on the treated wires. This effect permits a better quality paper to be produced, faster drying and sheet formation. Also, the invention permits greater variations in refining and machine speeds to be utilized.

We claim:

1. A method for improving, by chemical means, the operational efliciency of a Fourdrinier paper making machine which utilizes a coninuous Fourdrinier wire upon which paper and paper products are formed, which comprises treating the bottom of said Fourdrinier wire with a. dilute aqueous solution which contains at least .005 pound per ton, based on the dry weight of the paper and paper products formed on said Fourdrinier wire, of a composition having the formula: (A) from 598% by weight of water soluble, extreme pressure lubricant comprising a nitrogen-containing heterocyclic compound characterized by a ring nitrogen bonded to a ring carbon to which is attached a sulfhydryl group, and (B) from 295% by weight of a water miscible dispersing agent from the group formula:

(021110) nrt where R is an alkyl group of from 8 to 20 carbon atoms and n is a positive integer having a value of not more than 20.

4. The method for improving, by chemical means, the operational efficiency of Fourdrinier paper making machines in accordance with claim 1 wherein the water miscible, anionic dispersing agent is water miscible alkali metal lignosulfonate.

5. The method for improving, by chemical means, the operational efiiciency of Fourdrinier paper making machines in accordance with claim 1 wherein the composition also contains from 0.01 to 5% by weight of a water dispersible, organic silicon-containing compound from the group consisting of organo-silicon oxide condensation products and organo functional silanes.

6. The method for improving, by chemical means, the operational efliciency of Fourdrinier paper making machines in accordance with claim 5 where the organo function silane is an amino functional silane of the formula:

where R is a lower aliphatic hydrocarbon group of not more than 4 carbon atoms in chain length and Y is an aliphatic amine-containing group and n has the value of 01.

7. A method for improving, by chemical means, the operational efiiciency of a Fourdrinier paper making machine of the type utilizing a continuous Fourdrinier wire upon which paper and paper products are formed, and a breast roll and a couch roll as the main driving rolls for the Fourdrinier wire, which comprises treating the bottom of the Fourdrinier wire at a point after its contact with the couch roll, but before its subsequent contact with the breast roll, with a dilute aqueous solution which contains at least .005 pound per ton, based on the dry weight of the paper and paper products formed on said Fourdrinier wire, of a composition having the formula: (A) from 595% by weight of an alkali metal-2-mercaptobenzothiazole and (B) from 295% by weight of water miscible, nonionic dispersing agent having the general structural formula:

where R is an alkyl group of from 8 to 20 carbon atoms and n is a positive integer having a value of not more than 20.

References Cited in the file of this patent UNITED STATES PATENTS 1,216,861 Shorey Feb. 20, 1917 2,825,693 Beaubien Mar. 4, 1958 2,947,703 Lasonneur Aug. 2, 1960 2,992,469 Hose July 18, 1961 2,999,064 Sluhan Sept. 5, 1961 FOREIGN PATENTS 523,793 Canada Apr. 10, 1956 OTHER REFERENCES Paper Industry and Paper Word, page 903, October 1944.

Pye: Wear of Fourdrinier Wire Bearing Materials, from Pulp and Paper Magazine of Canada, pp. 124136, March 1958.

Some Corrosion Inhibitors From Corrosion, Vol. 11, No. 4, pp. 65, 66, and 67, April 1955. 

1. A METHOD OF IMPRIVING, BY CHEMICAL MEANS, THE OPERATIONAL EFFICIENCY OF A FOURDRINIER PAPER MAKING MACHINE WHICH UTILIZES A CONTINUOUS FOURDRINIER WIRE UPON WHICH PAPER AND PAPER PRODUCTS ARE FORMED, WHICH COMPRISES TREATING THE BOTTOM OF SAID FOURDRINIER WIRE WITH A DILUTE AQUEOUS SOLUTION WHICH CONTAINS AT LEAST .005 POUND PER TON, BASED ON THE DRY WEIGHT OF THE PAPER AND PAPER PRODUCTS FORMED ON SAID FOURDRINIER WIRE, OF A COMPOSITION HAVING THE FORMULA: (A) FROM 5-98% BY WEIGHT OF WATER SOLUBLE, EXTERME PRESSURE LUBRICANT COMPRISING A NITROGEN-CONTAINING HETEROCYCLIC COMPOUND CHARACTERIZED BY A RING NITROGEN BONDED TO A RING CARBON TO WHICH IS ATTACHED A SULIHYDRYL GROUP, AND (B) FROM 2-95% BY WEIGHT OF A WATER MISCIBLE DISPERSING AGENT FROM THE GROUP CONSISTING OF WATER MISCIBLE, NON-IONIC AND ANIONIC DISPERSING AGENTS. 